How to preload data in ion-autocomplete

In my ionic application i am using ion-autocomplete to load certain values from an api call. it works fine when user gives some input.but i am trying to preload all the data initially if user dont type anything. how can this be achieved?

here is my code.

view

<input ion-autocomplete type="text" ng-model="customer"
placeholder="Customers"  ng-click="getCustomers('1',customers)" 
items-method="getCustomers(query,customers)" 
item-view-value-key="company_name" items-clicked-method="setUser(callback,customers)" 
class="ion-autocomplete"   />

controller

 $scope.getCustomers = function (query, model) {

          var url = $rootScope.basicurl + "customers/customerName?customers=" + query + "&" + $scope.customertype + "=1";

            return $http.get(url, {


                headers: {
                    APIKEY: $localStorage.get('API_KEY')
                }

            }).then(function (response) {

                $scope.customerList = response.data;
                   return $scope.customerList;

            });

i tried calling the controller function on ng-click even though the function gets called it wont give the autocomplete.

Please help. thanks